ci: Possible fix for CI_SERVER issue in VLS CI

[ksedgwic]

Code using CI_SERVER was added recently to track something. It attempts to short-cut if CI_SERVER is not set, but on gitlab it is set to yes. https://docs.gitlab.com/ee/ci/variables/

Instead use CI_SERVER_URL, maybe that is what is intended?

VLS CI was failing on all skipped tests with:

=================================== FAILURES ===================================
�[31m�[1m_____________________ test_bookkeeping_missed_chans_pushed _____________________�[0m
[gw6] linux -- Python 3.10.12 /usr/bin/python3

pyfuncitem = <Function test_bookkeeping_missed_chans_pushed>

    @pytest.hookimpl(hookwrapper=True)
    def pytest_pyfunc_call(pyfuncitem):
        global result
        result = result.copy()
        result["testname"] = pyfuncitem.name
        result["start_time"] = int(time())
        outcome = yield
        result["end_time"] = int(time())
        # outcome.excinfo may be None or a (cls, val, tb) tuple
    
        if outcome.excinfo is None:
            result["outcome"] = "success"
        elif outcome.excinfo[0] == unittest.case.SkipTest:
            result["outcome"] = "skip"
        else:
            result["outcome"] = "fail"
    
        print(result)
    
        if not server:
            return
    
        try:
>           req = request.Request(f"{server}/hook/test", method="POST")

�[1m�[31mconftest.py�[0m:60: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
�[1m�[31m/usr/lib/python3.10/urllib/request.py�[0m:322: in __init__
    self.full_url = url
�[1m�[31m/usr/lib/python3.10/urllib/request.py�[0m:348: in full_url
    self._parse()
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 

self = <urllib.request.Request object at 0x7f06c1b99270>

    def _parse(self):
        self.type, rest = _splittype(self._full_url)
        if self.type is None:
>           raise ValueError("unknown url type: %r" % self.full_url)
�[1m�[31mE           ValueError: unknown url type: 'yes/hook/test'�[0m

�[1m�[31m/usr/lib/python3.10/urllib/request.py�[0m:377: ValueError

�[33mDuring handling of the above exception, another exception occurred:�[0m

[vincenzopalazzo]

utACK 050e8b8

[cdecker]

ACK 050e8b8